A transparent electromagnetic shielding film and its preparation method

Abstract

The present disclosure belongs to the technical field of electromagnetic shielding materials, and provides a transparent electromagnetic shielding film and a preparation method thereof. The shielding film includes a first shielding layer, a first anti-reflection layer, a base layer, a second anti-reflection layer, and a second shielding layer arranged in sequence from bottom to top; the first shielding layer and the second shielding layer are metal layers provided with the same grid pattern, and the grid patterns of the two shielding layers are exactly the same relative to the base layer. Preparation method: deposit the first anti-reflection layer and the second anti-reflection layer on both sides of the base layer; deposit the first metal layer and the second metal layer on the side of the two anti-reflection layers away from the base layer respectively; apply photoresist on the side of the two metal layers away from their adjacent anti-reflection layers, expose the two photoresists, form a completely aligned first grid pattern and a second grid pattern, and complete the preparation of the first shielding layer and the second shielding layer. The shielding film disclosed in the present disclosure has a simple structure and uses a double-sided aligned metal grid, which can simultaneously improve its shielding effectiveness and light transmittance.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electromagnetic shielding materials, and in particular to a transparent electromagnetic shielding film and a preparation method thereof. Background Art

[0002] The widespread use of electronic equipment has led to electromagnetic waves from working devices interfering with each other, causing them to fail, affecting human health, and even causing the leakage of state secrets. Therefore, the demand for electromagnetic shielding materials has arisen accordingly.

[0003] For application scenarios similar to window displays, in addition to the shielding effectiveness of the material, there are also high requirements for its transparency. In related technologies, metal grids are usually selected as shielding layers. The period of the metal grid is much larger than the optical wavelength and much smaller than the electromagnetic wavelength, thus achieving a good shielding effect and meeting basic electromagnetic shielding performance and light transmission performance.

[0004] In order to obtain higher shielding effectiveness, some technologies usually choose to increase the thickness of the metal mesh or increase the coverage area of ​​the metal in the metal mesh. However, the increase in the thickness of the metal mesh will reduce its bonding performance, and the increase in the metal coverage area will reduce the transmittance of the overall material. In addition, some technologies will set two conductive mesh layers at the same time, such as a transparent electromagnetic interference shielding film, which is sequentially provided with a first transparent polymer substrate layer, a first conductive mesh layer, a second transparent polymer substrate layer, and a second conductive mesh layer, wherein the first conductive mesh layer and the second conductive mesh layer are respectively provided on the first transparent polymer substrate layer and the second transparent polymer substrate layer by printing; and the two conductive mesh layers are arranged in a manner of overlapping or misalignment with each other. This technology has the following defects: (1) The structure is complex and two substrate layers need to be provided; (2) The setting of two substrate layers will reduce the transmittance; (3) The preparation method of printing and bonding is difficult to achieve precise positioning, which will inevitably lead to misalignment between the two conductive mesh layers and reduce the transmittance.

[0005] Therefore, it is necessary to provide a transparent electromagnetic shielding film with high shielding effectiveness and light transmittance and simple structure. Summary of the invention

[0006] The present disclosure provides a transparent electromagnetic shielding film and a preparation method thereof, so as to at least solve the above technical problems existing in the prior art.

[0007] According to a first aspect of the present disclosure, a transparent electromagnetic shielding film is provided, comprising a first shielding layer, a first anti-reflection layer, a base layer, a second anti-reflection layer, and a second shielding layer arranged in sequence from bottom to top; the first shielding layer and the second shielding layer are metal layers provided with a grid pattern, the grid patterns of the first shielding layer and the second shielding layer are the same, and their positions relative to the base layer are exactly the same.

[0008] Specifically, although the preparation of double-sided metal grids can improve the shielding effectiveness, if the double-sided metal grids are only randomly stacked without precise alignment, even if the anti-reflection film is plated on both sides, it is still impossible to achieve a high transmittance. Therefore, the positions of the grid patterns of the first shielding layer and the second shielding layer in the present disclosure overlap, that is, a double-sided aligned metal grid is used. With such a design, the shielding effectiveness and transmittance of the transparent electromagnetic shielding film can be improved at the same time.

[0009] In one possible implementation, the grid pattern is arranged in a periodic arrangement or a non-periodic arrangement.

[0010] In a preferred embodiment, the grid pattern is arranged in a periodic manner.

[0011] In one possible implementation manner, when the grid pattern is arranged in a periodic arrangement and the total area of ​​the grid pattern in the metal layer is ≤20%, the transmittance of the first shielding layer or the second shielding layer is ≥80%, and the shielding effectiveness is ≥30dB.

[0012] In one embodiment, the thickness of the metal layer is 0.05-10 μm.

[0013] In a preferred embodiment, the thickness of the metal layer is 0.5-6 μm.

[0014] In one embodiment, the material of the metal layer is selected from at least one of a conductive metal and a conductive alloy.

[0015] In a preferred embodiment, the material of the metal layer is selected from at least one of Al, Cu, Au, Ag, Ti, Ni, and NiCr alloy.

[0016] In one embodiment, the thickness of the first anti-reflection layer and the second anti-reflection layer are both 0.1-10 μm.

[0017] In a preferred embodiment, the thickness of the first anti-reflection layer and the second anti-reflection layer are both 0.5-5 μm.

[0018] Specifically, the transparent electromagnetic shielding film disclosed herein has an anti-reflection layer disposed between the base layer and the shielding layer, which has the effect of improving the light transmittance without affecting the shielding effectiveness.

[0019] In one possible implementation, the refractive indexes of the first anti-reflection layer and the second anti-reflection layer are both 1-4.

[0020] In one embodiment, the material of the first anti-transmittance layer and the second anti-transmittance layer is selected from at least one of Nb2O5, TiO2, ZnO, ZrO2, MgF2, SiO2, Ge, ZnS, ZnSe, AlF3, Al2O3, HfO2, Ta2O5, YbF3, YF3, and SrF2.

[0021] Specifically, the materials of the first anti-reflection layer and the second anti-reflection layer are selected from dielectric materials or semiconductor materials that have no absorption in the target anti-reflection band.

[0022] In one embodiment, the materials of the first anti-reflection layer and the second anti-reflection layer are the same or different.

[0023] Specifically, when it is necessary to anti-reflect the incident light in a narrower band, the first anti-reflection layer and the second anti-reflection layer made of the same material can be used; when it is necessary to anti-reflect the incident light in a wider band, the first anti-reflection layer and the second anti-reflection layer made of different materials can be used. In this case, the first anti-reflection layer and the second anti-reflection layer each reduce reflection and enhance transmittance of a part of the wavelengths of the incident light.

[0024] For example, when only the visible light band needs to be enhanced, the first and second anti-transmittance layers can both be SiO2; when only the infrared band needs to be enhanced, the first and second anti-transmittance layers can both be YbF3; when both the visible light and infrared bands need to be enhanced, one of the first and second anti-transmittance layers can be SiO2 and the other can be YbF3.

[0025] Specifically, anti-reflection layers for different wavelength ranges can be plated on both sides, which can also achieve the effect of wide-spectrum anti-reflection and anti-reflection to a certain extent, thereby improving the average transmittance of the wide spectrum.

[0026] In one embodiment, the base layer has a thickness of 0.01 to 5 mm.

[0027] In one embodiment, the refractive index of the base layer is 1-3.

[0028] In one embodiment, the material of the base layer is selected from transparent materials with a transmittance ≥ 90%, including but not limited to PET, TAC, CPI, PMMA, glass, quartz, sapphire, ZnS, ZnSe, BaF2, etc.

[0029] According to a second aspect of the present disclosure, there is provided a method for preparing the transparent electromagnetic shielding film, comprising the following steps:

[0030] S1: providing a base layer, depositing a first anti-reflection layer on the lower surface of the base layer, and depositing a second anti-reflection layer on the upper surface of the base layer;

[0031] S2: depositing a first metal layer and a second metal layer on a side of the first anti-reflection layer away from the base layer and a side of the second anti-reflection layer away from the base layer respectively; coating a first photoresist and a second photoresist on a side of the first metal layer away from the first anti-reflection layer and a side of the second metal layer away from the second anti-reflection layer respectively, marking at least two positioning points in one of the first photoresist and the second photoresist, and exposing one of the first photoresist and the second photoresist to form a first grid pattern; then capturing the positioning points with the other photoresist and positioning the exposure to form a second grid pattern that is completely aligned with the first grid pattern, and at this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0032] In one embodiment, step S1 further includes the step of pre-treating the base layer: plasma cleaning the base layer to remove surface impurities.

[0033] In one embodiment, step S1 deposits the first anti-reflection layer and the second anti-reflection layer by magnetron sputtering.

[0034] Specifically, before performing the magnetron sputtering, the target material is pre-sputtered to remove oxides on the surface of the target material.

[0035] Specifically, the vacuum degree of the pre-sputtering is 1.0×10 -4 ~3.0×10 -3 Pa.

[0036] Specifically, the conditions of the magnetron sputtering include: a vacuum degree of 1.0×10 -4 ~3.0×10 -3 Pa, the deposition atmosphere is an inert gas or a mixed atmosphere of an inert gas and O2, the gas flow rate is 20-80sccm, and the sputtering power is 50-200W.

[0037] Specifically, the target material is selected from a ceramic target material or a metal target material.

[0038] In one embodiment, after the first anti-reflection layer and the second anti-reflection layer are prepared, step S1 further includes an annealing process, and the specific steps are as follows: the first anti-reflection layer is irradiated with ultraviolet light on the side away from the base layer and the second anti-reflection layer is irradiated with ultraviolet light on the side away from the base layer, and the wavelength of the ultraviolet light is 240 to 300 nm, and the power is 100 to 150 mW / cm 2 The irradiation time is 10 to 20 minutes.

[0039] Specifically, the ultraviolet light irradiation treatment can improve the surface flatness of the first anti-reflection layer and the second anti-reflection layer, enhance the bonding force between the anti-reflection layer and the shielding layer, and enhance the light transmittance of the overall electromagnetic shielding film.

[0040] In one embodiment, step S2 deposits the first metal layer and the second metal layer by magnetron sputtering.

[0041] Specifically, before performing the magnetron sputtering, the target material is pre-sputtered to remove oxides on the surface of the target material.

[0042] Specifically, the vacuum degree of the pre-sputtering is 1.0×10 -4 ~3.0×10 -3 Pa.

[0043] Specifically, the conditions of the magnetron sputtering include: a vacuum degree of 1.0×10 -4 ~3.0×10 -3 Pa, the deposition atmosphere is an inert gas, the gas flow rate is 20-80sccm, and the sputtering power is 30-200W.

[0044] Specifically, the target material is selected from a single metal target.

[0045] In one possible implementation manner, the specific steps of forming the first grid pattern and the second grid pattern in step S2 include: using a mask photolithography method: covering the surfaces of the first photoresist and the second photoresist with a mask having a grid pattern, marking at least two positioning points in one of the first photoresist and the second photoresist, and exposing one of the first photoresist and the second photoresist to form the first grid pattern; capturing the positioning points according to visible light or infrared light to fully align the mask covering the surfaces of the first photoresist and the second photoresist; exposing the other photoresist covered with the mask to form the second grid pattern;

[0046] Alternatively, a maskless direct-write exposure method is used: at least two positioning points are marked in one of the first photoresist and the second photoresist, and one of the first photoresist and the second photoresist is exposed to form the first gridded pattern, and the coordinates of the positioning points are recorded as first coordinates; the positioning points are captured on the other photoresist and recorded as second coordinates; the position of the second exposure is obtained by calculating the first coordinates and the second coordinates, and the other photoresist is exposed to form the second gridded pattern that is completely aligned with the first gridded pattern.

[0047] In one embodiment, the maskless direct writing exposure method is a sequential direct writing exposure. At least two positioning points are marked in one of the first photoresist and the second photoresist, and one of the first photoresist and the second photoresist is exposed to form the first grid pattern, and the coordinates of the positioning points are recorded as first coordinates, and the first coordinates contain the coordinate position data of each of the above positioning points; the above positioning points are captured on the other photoresist and recorded as second coordinates, and the second coordinates also contain the coordinate position data of each of the above positioning points; the coordinate position data of each positioning point in the first coordinates is compared with the coordinate position data of each positioning point in the second coordinates corresponding to the first coordinates, and the position of the second exposure is obtained by calculation, and the other photoresist is exposed for the second time to form the second grid pattern that is completely aligned with the first grid pattern.

[0048] Specifically, the sequential direct writing exposure is a same-side exposure, in which case the exposure sources of the two exposures are located on the same side of the film material. After comparing the first coordinate with the second coordinate, the offset azimuth and offset distance of the second coordinate relative to the first coordinate are calculated, and the azimuth and distance required for position correction of the second exposure are calculated based on the offset azimuth and offset distance, so as to locate the position of the second exposure, and then the second exposure is performed on the other photoresist to form a second grid pattern that is completely aligned with the first grid pattern.

[0049] Specifically, the sequential direct writing exposure is opposite-side exposure, and the exposure sources of the two exposures are located on opposite sides of the film. After comparing the first coordinate with the second coordinate, the position information of the first coordinate relative to the first exposure area is calculated, and the position of the second exposure area relative to the second coordinate is calculated based on the position information, and then the second exposure is performed on another photoresist to form a second grid pattern that is completely aligned with the first grid pattern.

[0050] In one embodiment, the maskless direct writing exposure method can also be a double-sided simultaneous direct writing exposure method, wherein at least two positioning points are marked in one of the first photoresist and the second photoresist, and after the positioning points are captured on the first photoresist and the second photoresist, exposure is performed simultaneously, and a first grid pattern and a second grid pattern that is completely aligned with the first grid pattern are formed simultaneously.

[0051] In one possible implementation manner, when the maskless direct writing exposure method is adopted, a maskless direct writing device is used; the maskless direct writing device is equipped with a visible light or infrared light double-sided alignment device or a single-sided alignment device.

[0052] In one embodiment, after forming the first grid pattern and the second grid pattern, step S2 further includes a development step: developing the first photoresist and the second photoresist after exposure, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist.

[0053] In a preferred embodiment, after forming the first grid pattern and the second grid pattern, step S2 further includes a development step: for the mask photolithography method, removing the mask, developing the first photoresist and the second photoresist after exposure, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresists;

[0054] Alternatively, for the maskless direct writing exposure method, the first photoresist and the second photoresist after exposure are directly developed, the photoresists in the first grid pattern and the second grid pattern are retained, and the remaining photoresists are removed.

[0055] In one possible implementation, after the development is performed, step S2 further includes the following steps: wet etching the developed film material structure to retain the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; then removing the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern, and the preparation of the first shielding layer and the second shielding layer is completed.

[0056] Specifically, the pH of the wet etching solution is ≤7.

[0057] Specifically, the wet etching time is 0.1 to 2 minutes.

[0058] Specifically, acetone or a stripping agent is used to remove the photoresist in the first grid pattern and the second grid pattern.

[0059] More specifically, when removing the photoresist, it is placed in an ultrasonic or water bath environment and removed using the acetone or the stripping agent.

[0060] According to an implementation method of the present disclosure, at least the following beneficial effects are achieved:

[0061] The transparent electromagnetic shielding film disclosed in the present invention has a simple structure, requires only one base layer, and has high light transmittance. An anti-reflection layer is arranged between the base layer and the shielding layer, and anti-reflection layers for different wavelength ranges can be plated on both sides, which can also achieve the effect of wide-spectrum anti-reflection and anti-reflection to a certain extent, and can improve the wide-spectrum average light transmittance without affecting the shielding effectiveness; in addition, the positions of the grid patterns of the first shielding layer and the second shielding layer disclosed in the present invention overlap, that is, the electromagnetic shielding film uses a double-sided aligned metal grid, and such a design can simultaneously improve the shielding effectiveness and light transmittance of the transparent electromagnetic shielding film.

[0062] The present invention can ensure the precise overlap of the positions of the shielding layers on both sides by optimizing the preparation method, so that the transparent electromagnetic shielding film has both high shielding efficiency and light transmittance.

[0063] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0065] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0066] Figure 1 A schematic structural diagram of a transparent electromagnetic shielding film in a specific embodiment of the present disclosure is shown;

[0067] Figure 2 A flow chart of defining a photoresist pattern using a conventional mask lithography method in Embodiment 3 of the present disclosure is shown.

[0068] Reference numerals:

[0069] 1-base layer; 21-first anti-reflection layer; 22-second anti-reflection layer; 31-first shielding layer; 32-second shielding layer; 33-first metal layer; 34-second metal layer; 35-first metal layer corresponding to the first grid pattern; 36-second metal layer corresponding to the second grid pattern; 41-first photoresist; 42-second photoresist; 43-first photoresist after exposure; 44-second photoresist after exposure; 45-photoresist with the first grid pattern; 46-photoresist with the second grid pattern; 5-mask. DETAILED DESCRIPTION

[0070] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0071] The present disclosure provides a transparent electromagnetic shielding film, such as Figure 1 As shown, it includes a first shielding layer 31, a first anti-reflection layer 21, a base layer 1, a second anti-reflection layer 22, and a second shielding layer 32 which are arranged in sequence from bottom to top; the first shielding layer 31 and the second shielding layer 32 are metal layers provided with a grid pattern, and the grid patterns of the first shielding layer 31 and the second shielding layer 32 are the same, and their positions relative to the base layer 1 are exactly the same.

[0072] Example 1

[0073] In this embodiment, a transparent electromagnetic shielding film 1 is prepared, and the specific process is as follows:

[0074] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0075] (2) Depositing a first anti-reflection layer on the lower surface of the transparent substrate and depositing a second anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0076] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0077] 2) Deposit the first anti-reflection layer on the lower surface (front) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and the SiO2 first anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained;

[0078] 3) Deposit the second anti-reflection layer on the upper surface (reverse side) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3Pa, the target material is selected as SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a SiO2 second anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained.

[0079] (3) preparing a first shielding layer and a second shielding layer on a side of the first anti-reflection layer facing away from the PET transparent substrate and on a side of the second anti-reflection layer facing away from the PET transparent substrate respectively:

[0080] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0081] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the side of the first anti-reflection layer away from the PET transparent substrate and the side of the second anti-reflection layer away from the PET transparent substrate, respectively. The specific process parameters are: vacuum degree 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0082] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the first anti-reflection layer and the side of the second metal layer away from the second anti-reflection layer respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0083] 4) Define the photoresist pattern: Use a maskless same-side sequential direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to mark three positioning points on the first photoresist, perform a first exposure on the first photoresist to form a first grid pattern, and record the first coordinates containing the position information of the three positioning points; capture the position information of the three positioning points on the second photoresist and record it as the second coordinates; calculate the area for the second exposure based on the first coordinates and the second coordinates, and then expose the second photoresist to form a second grid pattern that is completely aligned with the first grid pattern;

[0084] 5) Development: directly developing the first photoresist and the second photoresist after exposure for 60 seconds, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist;

[0085] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0086] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0087] The transparent electromagnetic shielding film 1 has an average shielding effectiveness of 60 dB in the range of 0.3 to 18 GHz and an average transmittance of 86% in the visible light band (400 to 700 nm).

[0088] Example 2

[0089] In this embodiment, a transparent electromagnetic shielding film 2 is prepared, and the specific process is as follows:

[0090] (1) A CPI transparent substrate with a thickness of 1 mm is provided and pretreated: the CPI transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0091] (2) Depositing a first anti-reflection layer on the lower surface of the transparent substrate and depositing a second anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0092] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0093] 2) Deposit the first anti-reflection layer on the lower surface (front) of the CPI transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, select Si target as target, the deposition atmosphere is a mixed atmosphere of Ar and O2, the gas flow rate is 25sccm, the sputtering power is 120W, the sputtering time is 20min, and the first SiO2 anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained;

[0094] 3) Deposit the second anti-reflection layer on the upper surface (reverse side) of the CPI transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is selected as Ta2O5 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 40sccm, the sputtering power is 100W, the sputtering time is 30min, and a Ta2O5 second anti-reflection layer with a thickness of 0.1μm and a refractive index of 2.2 is obtained.

[0095] (3) preparing a first shielding layer and a second shielding layer on the side of the first anti-reflection layer away from the CPI transparent substrate and on the side of the second anti-reflection layer away from the CPI transparent substrate respectively:

[0096] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0097] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the side of the first anti-reflection layer away from the CPI transparent substrate and the side of the second anti-reflection layer away from the CPI transparent substrate, respectively. The specific process parameters are: vacuum degree 3.0×10 -3 Pa, the target material is a single Al target, the deposition atmosphere is high-purity Ar, the gas flow rate is 40sccm, the sputtering power is 100W, the sputtering time is 25min, and an Al metal layer with a thickness of 1μm is obtained;

[0098] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the first anti-reflection layer and the side of the second metal layer away from the second anti-reflection layer respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0099] 4) Defining the photoresist pattern: Using a maskless same-side sequential direct writing exposure method: using a maskless direct writing lithography machine (MLA150), marking 4 positioning points on the first photoresist, performing a first exposure on the first photoresist to form a first grid pattern, and recording a first coordinate containing the position information of the 4 positioning points; capturing the position information of the 4 positioning points on the second photoresist, and recording it as a second coordinate; calculating the area for the second exposure according to the first coordinate and the second coordinate, and then exposing the second photoresist to form a second grid pattern that is completely aligned with the first grid pattern;

[0100] 5) Development: directly developing the first photoresist and the second photoresist after exposure for 60 seconds, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist;

[0101] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; wherein the etching solution is an acidic HCl solution with a pH value of ≤7, and the etching time is 0.7 min;

[0102] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0103] The transparent electromagnetic shielding film 2 has an average shielding effectiveness of 63 dB at 0.3-18 GHz, an average transmittance of 84% in the visible light band (400-700 nm), and an average transmittance of 85% in the ultraviolet band (300-420 nm).

[0104] Example 3

[0105] This embodiment prepares a transparent electromagnetic shielding film 3. The specific process is as follows: Figure 2 The process diagram shown is as follows:

[0106] (1) A PMMA transparent substrate (substrate layer 1) with a thickness of 4 mm was provided and pretreated: the PMMA transparent substrate was placed in deionized water for plasma cleaning for 5 min to remove surface impurities, and then dried in a N2 atmosphere.

[0107] (2) By magnetron sputtering, a first anti-reflection layer 21 is deposited on the lower surface of the transparent substrate, and a second anti-reflection layer 22 is deposited on the upper surface of the transparent substrate:

[0108] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0109] 2) Depositing the first anti-reflection layer 21 on the lower surface (front surface) of the PMMA transparent substrate: Evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, select the target material as YbF3 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 60sccm, the sputtering power is 180W, the sputtering time is 30min, and the YbF3 first anti-reflection layer with a thickness of 8.7μm and a refractive index of 1.52 is obtained;

[0110] 3) Depositing the second anti-reflection layer 22 on the upper surface (reverse side) of the PMMA transparent substrate: Evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is selected as SrF2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 55sccm, the sputtering power is 100W, the sputtering time is 30min, and the SrF2 second anti-reflection layer with a thickness of 2.5μm and a refractive index of 1.44 is obtained.

[0111] (3) A first shielding layer 31 and a second shielding layer 32 are respectively prepared on the side of the first anti-reflection layer 21 away from the PMMA transparent substrate and on the side of the second anti-reflection layer 22 away from the PMMA transparent substrate:

[0112] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0113] 2) The coating environment is evacuated, and the first metal layer 33 and the second metal layer 34 are deposited on the side of the first anti-reflection layer 21 away from the PMMA transparent substrate and the side of the second anti-reflection layer 22 away from the PMMA transparent substrate, respectively. The specific process parameters are: vacuum degree 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 60sccm, the sputtering power is 120W, the sputtering time is 42min, and a Cu metal layer with a thickness of 8μm is obtained;

[0114] 3) A first photoresist 41 and a second photoresist 42 are respectively coated on the side of the first metal layer 33 away from the first anti-reflection layer 21 and the side of the second metal layer 34 away from the second anti-reflection layer 22 (see Figure 2 a), put it into an oven to bake to fix the photoresist; the photoresist used is AZ4562, the spin coating speed is 3600rpm, the spin coating cycle is 20s, the baking temperature is 110°C, and the baking time is 30min;

[0115] 4) Define the photoresist pattern: Use the traditional mask lithography method: Cover the surfaces of the first photoresist 41 and the second photoresist 42 with a mask 5 with a grid pattern respectively, capture the coordinates of the two diagonal points of the two mask plates 5 with infrared, and fine-tune the positions of the mask plates 5 so that the coordinates of the diagonal points of the two mask plates 5 correspond to each other and completely overlap, ensuring that the first grid pattern and the second grid pattern of the two mask plates 5 are completely aligned (see Figure 2 b); the film material covered with the mask 5 is exposed to transfer the first grid pattern and the second grid pattern to the photoresist to form a first photoresist 43 after exposure and a second photoresist 44 after exposure (see Figure 2 c);

[0116] 5) Development: Remove the mask 5, develop the first photoresist 43 and the second photoresist 44 after exposure, retain the photoresist 45 in the first grid pattern and the photoresist 46 in the second grid pattern, and remove the remaining photoresists (see Figure 2 d);

[0117] 6) Wet etching is performed on both sides of the film material at the same time, retaining the first metal layer 35 corresponding to the first grid pattern and the second metal layer 36 corresponding to the second grid pattern, and removing the remaining metal layers (see Figure 2 e); wherein the etching solution is an acidic CuCl2 solution with a pH value of ≤7, and the etching time is 2min;

[0118] 7) Acetone is applied to the film material to remove the photoresist 45 in the first grid pattern and the photoresist 46 in the second grid pattern, thereby obtaining a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer 31 and the second shielding layer 32 is completed (see Figure 2 f).

[0119] The transparent electromagnetic shielding film 3 has an average shielding effectiveness of 71 dB at 0.3-18 GHz, an average transmittance of 82% in the visible light band (400-700 nm), and an average transmittance of 91% in the near infrared band (0.7-2.5 μm).

[0120] Example 4

[0121] In this embodiment, a transparent electromagnetic shielding film 4 is prepared, and the specific process is as follows:

[0122] (1) A TAC transparent substrate with a thickness of 0.5 mm was provided and pretreated: the TAC transparent substrate was placed in deionized water for plasma cleaning for 5 min to remove surface impurities, and then dried in a N2 atmosphere.

[0123] (2) Depositing a first anti-reflection layer on the lower surface of the transparent substrate and depositing a second anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0124] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 1.0×10 -4 Pa;

[0125] 2) Deposit the first anti-reflection layer on the lower surface (front) of the TAC transparent substrate: evacuate the coating environment and maintain the vacuum degree at 1.0×10 -4 Pa, the target material is selected as Ge metal target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and the Ge first anti-reflection layer with a thickness of 0.6μm and a refractive index of 2.66 is obtained;

[0126] 3) Deposit the second anti-reflection layer on the upper surface (reverse side) of the TAC transparent substrate: evacuate the coating environment and maintain the vacuum degree at 1.0×10 -4 Pa, the target material is selected as Ge metal target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a Ge second anti-reflection layer with a thickness of 0.15μm and a refractive index of 2.66 is obtained.

[0127] (3) A first shielding layer and a second shielding layer are respectively prepared on the side of the first anti-reflection layer facing away from the TAC transparent substrate and the side of the second anti-reflection layer facing away from the TAC transparent substrate:

[0128] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 1.0×10 -4 Pa;

[0129] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the side of the first anti-reflection layer away from the TAC transparent substrate and the side of the second anti-reflection layer away from the TAC transparent substrate, respectively. The specific process parameters are: vacuum degree is 1.0×10 -4 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0130] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the first anti-reflection layer and the side of the second metal layer away from the second anti-reflection layer respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0131] 4) Defining the photoresist pattern: using a conventional mask lithography method: covering the surfaces of the first photoresist and the second photoresist with a mask having a grid pattern respectively, emitting visible light to capture the coordinates of the two diagonal points of the two mask plates, and recording the coordinates of the diagonal points, and fine-tuning the positions of the mask plates so that the coordinates of the diagonal points of the two mask plates correspond one to one and completely overlap, ensuring that the first grid pattern and the second grid pattern of the two mask plates are completely aligned; exposing the film material covered with the mask plates to transfer the first grid pattern and the second grid pattern to the photoresist;

[0132] 5) Development: removing the mask, developing the first photoresist after exposure and the second photoresist after exposure, retaining the photoresist in the first grid pattern and the photoresist in the second grid pattern, and removing the remaining photoresists;

[0133] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer corresponding to the first grid pattern and the second metal layer corresponding to the second grid pattern, and removing the remaining metal layers; wherein the etching solution is an acidic CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0134] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the photoresist in the second grid pattern, thereby obtaining a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0135] The above-mentioned transparent electromagnetic shielding film 4 has an average shielding effectiveness of 60dB at 0.3-18GHz, an average transmittance of 84% in the visible light band (400-700nm), an average transmittance of 88% in the near infrared band (0.7-2.5μm), and an average transmittance of 94% in the mid-infrared band (2.5-25μm).

[0136] Example 5

[0137] In this embodiment, a transparent electromagnetic shielding film 5 is prepared, and the specific process is as follows:

[0138] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0139] (2) Depositing a first anti-reflection layer on the lower surface of the transparent substrate and depositing a second anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0140] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0141] 2) Deposit the first anti-reflection layer on the lower surface (front) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and the SiO2 first anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained;

[0142] 3) Deposit the second anti-reflection layer on the upper surface (reverse side) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is selected as SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a SiO2 second anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained.

[0143] 4) The surfaces of the two anti-reflection layers were treated with ultraviolet light at a wavelength of 256 nm and a power of 100 mW / cm 2 , the irradiation time is 20min.

[0144] (3) preparing a first shielding layer and a second shielding layer on a side of the first anti-reflection layer facing away from the PET transparent substrate and on a side of the second anti-reflection layer facing away from the PET transparent substrate respectively:

[0145] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0146] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the side of the first anti-reflection layer away from the PET transparent substrate and the side of the second anti-reflection layer away from the PET transparent substrate, respectively. The specific process parameters are: vacuum degree 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0147] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the first anti-reflection layer and the side of the second metal layer away from the second anti-reflection layer respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0148] 4) Define the photoresist pattern: Use a maskless same-side sequential direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to mark three positioning points on the first photoresist, perform a first exposure on the first photoresist to form a first grid pattern, and record the first coordinates containing the position information of the three positioning points; capture the position information of the three positioning points on the second photoresist and record it as the second coordinates; calculate the area for the second exposure based on the first coordinates and the second coordinates, and then expose the second photoresist to form a second grid pattern that is completely aligned with the first grid pattern;

[0149] 5) Development: directly developing the first photoresist and the second photoresist after exposure for 60 seconds, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist;

[0150] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0151] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0152] The transparent electromagnetic shielding film 5 has an average shielding effectiveness of 60 dB in the range of 0.3 to 18 GHz and an average transmittance of 88% in the visible light band (400 to 700 nm).

[0153] Comparative Example 1

[0154] This comparative example prepares a transparent electromagnetic shielding film a, which is different from Example 1 in that no anti-reflection layer is prepared in this comparative example. The specific process is as follows:

[0155] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0156] (2) depositing a first shielding layer on the lower surface of the transparent substrate and a second shielding layer on the upper surface of the transparent substrate by magnetron sputtering:

[0157] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0158] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the lower surface and the upper surface of the PET transparent substrate respectively. The specific process parameters are: vacuum degree is 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0159] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the PET transparent substrate and the side of the second metal layer away from the PET transparent substrate respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0160] 4) Define the photoresist pattern: Use a maskless same-side sequential direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to mark three positioning points on the first photoresist, perform a first exposure on the first photoresist to form a first grid pattern, and record the first coordinates containing the position information of the three positioning points; capture the position information of the three positioning points on the second photoresist and record it as the second coordinates; calculate the area for the second exposure based on the first coordinates and the second coordinates, and then expose the second photoresist to form a second grid pattern that is completely aligned with the first grid pattern;

[0161] 5) Development: directly developing the first photoresist and the second photoresist after exposure for 60 seconds, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist;

[0162] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0163] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0164] The transparent electromagnetic shielding film a has an average shielding effectiveness of 60 dB at 0.3 to 18 GHz and an average transmittance of 80% in the visible light band (400 to 700 nm).

[0165] Comparative Example 2

[0166] This comparative example prepares a transparent electromagnetic shielding film b, which is different from comparative example 1 in that this comparative example prepares a single shielding layer and a single anti-reflection layer. The specific process is:

[0167] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0168] (2) Depositing an anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0169] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0170] 2) Deposit an anti-reflection layer on the upper surface of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is selected as SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a SiO2 anti-reflection layer with a thickness of 0.15μm is obtained.

[0171] (3) Prepare a shielding layer on the side of the anti-reflection layer away from the PET transparent substrate:

[0172] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10-3 Pa;

[0173] 2) The coating environment is evacuated, and a metal layer is deposited on the side of the anti-reflection layer away from the PET transparent substrate. The specific process parameters are: vacuum degree is 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0174] 3) coating a photoresist on the side of the metal layer away from the anti-reflection layer, and baking it in an oven to fix the photoresist; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0175] 4) Define the photoresist pattern: Use a maskless direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to directly expose the photoresist to form a grid pattern;

[0176] 5) Development: Directly develop the exposed photoresist for 60 seconds, retain the photoresist in a grid pattern, and remove the rest of the photoresist;

[0177] 6) wet-etching the film material, retaining the metal layer corresponding to the grid pattern and removing the remaining metal layers; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0178] 7) Acetone is applied to the film material to remove the photoresist in the grid pattern, thereby obtaining a metal layer with a grid pattern, which is now a shielding layer.

[0179] The transparent electromagnetic shielding film b has an average shielding effectiveness of 35 dB at 0.3 to 18 GHz and an average transmittance of 82% in the visible light band (400 to 700 nm).

[0180] Comparative Example 3

[0181] This comparative example prepares a transparent electromagnetic shielding film c, which is different from Example 1 in that this comparative example prepares an anti-reflection layer. The specific process is as follows:

[0182] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0183] (2) Depositing an anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0184] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0185] 2) Deposit an anti-reflection layer on the upper surface of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is selected as SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a SiO2 anti-reflection layer with a thickness of 0.15μm is obtained.

[0186] (3) preparing a first shielding layer and a second shielding layer on the lower surface of the PET transparent substrate and on the side of the anti-reflection layer facing away from the PET transparent substrate respectively:

[0187] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0188] 2) The coating environment is evacuated, and the first metal layer and the second metal layer are deposited on the lower surface of the PET transparent substrate and the side of the anti-reflection layer away from the PET transparent substrate respectively. The specific process parameters are: vacuum degree is 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 0.6μm is obtained;

[0189] 3) coating the first photoresist and the second photoresist on the side of the first metal layer away from the PET transparent substrate and the side of the second metal layer away from the anti-reflection layer respectively, and baking them in an oven to fix the photoresists; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0190] 4) Define the photoresist pattern: Use a maskless same-side sequential direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to mark three positioning points on the first photoresist, perform a first exposure on the first photoresist to form a first grid pattern, and record the first coordinates containing the position information of the three positioning points; capture the position information of the three positioning points on the second photoresist and record it as the second coordinates; calculate the area for the second exposure based on the first coordinates and the second coordinates, and then expose the second photoresist to form a second grid pattern that is completely aligned with the first grid pattern;

[0191] 5) Development: directly developing the first photoresist and the second photoresist after exposure for 60 seconds, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist;

[0192] 6) wet etching is performed on both sides of the film material at the same time, retaining the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and removing the remaining metal layers; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 0.5 min;

[0193] 7) Acetone is applied to the film material to remove the photoresist in the first grid pattern and the second grid pattern to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

[0194] The transparent electromagnetic shielding film c has an average shielding effectiveness of 60 dB in the range of 0.3 to 18 GHz and an average transmittance of 82% in the visible light band (400 to 700 nm).

[0195] Comparative Example 4

[0196] This comparative example prepares a transparent electromagnetic shielding film d, which is different from Example 1 in that this comparative example prepares a shielding layer. The specific process is:

[0197] (1) A PET transparent substrate with a thickness of 0.5 mm is provided and pretreated: the PET transparent substrate is placed in deionized water for plasma cleaning for 5 minutes to remove surface impurities, and then dried in a N2 atmosphere.

[0198] (2) Depositing a first anti-reflection layer on the lower surface of the transparent substrate and depositing a second anti-reflection layer on the upper surface of the transparent substrate by magnetron sputtering:

[0199] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0200] 2) Deposit the first anti-reflection layer on the lower surface (front) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3 Pa, the target material is SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and the SiO2 first anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained;

[0201] 3) Deposit the second anti-reflection layer on the upper surface (reverse side) of the PET transparent substrate: evacuate the coating environment and maintain the vacuum degree at 3.0×10 -3Pa, the target material is selected as SiO2 ceramic target, the deposition atmosphere is 99.99% high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 100W, the sputtering time is 30min, and a SiO2 second anti-reflection layer with a thickness of 0.15μm and a refractive index of 1.45 is obtained.

[0202] (3) A shielding layer is prepared on the side of the first anti-reflection layer away from the PET transparent substrate:

[0203] 1) Pre-sputtering: Evacuate the coating environment and pre-sputter the target to remove oxides on the target surface. The vacuum degree is 3.0×10 -3 Pa;

[0204] 2) The coating environment is evacuated, and a metal layer is deposited on the side of the first anti-reflection layer away from the PET transparent substrate. The specific process parameters are: vacuum degree is 3.0×10 -3 Pa, the target material is a single-element Cu target, the deposition atmosphere is high-purity Ar, the gas flow rate is 30sccm, the sputtering power is 80W, the sputtering time is 30min, and a Cu metal layer with a thickness of 1.5μm is obtained;

[0205] 3) coating a photoresist on the side of the metal layer away from the first anti-reflection layer, and baking in an oven to fix the photoresist; the photoresist used is AZ4562, the spin coating speed is 3600 rpm, the spin coating cycle is 20 s, the baking temperature is 110° C., and the baking time is 30 min;

[0206] 4) Define the photoresist pattern: Use a maskless direct writing exposure method: Use a maskless direct writing lithography machine (MLA150) to directly expose the photoresist to form a grid pattern;

[0207] 5) Development: Directly develop the exposed photoresist for 60 seconds, retain the photoresist in a grid pattern, and remove the rest of the photoresist;

[0208] 6) Wet etching is performed on both sides of the film material at the same time, the metal layer corresponding to the grid pattern is retained, and the remaining metal layers are removed; wherein the etching solution is a CuCl2 solution with a pH value of ≤7, and the etching time is 1 min;

[0209] 7) Acetone is applied to the film material to remove the photoresist in a grid pattern, thereby obtaining a metal layer with a grid pattern. At this time, the preparation of the shielding layer is completed.

[0210] The transparent electromagnetic shielding film d has an average shielding effectiveness of 47 dB in the range of 0.3 to 18 GHz and an average transmittance of 87.3% in the visible light band (400 to 700 nm).

[0211] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0212] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0213] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A transparent electromagnetic shielding film, characterized in that: The invention comprises a first shielding layer, a first anti-reflection layer, a base layer, a second anti-reflection layer, and a second shielding layer which are sequentially arranged from bottom to top; the first shielding layer and the second shielding layer are metal layers provided with a grid pattern, the grid patterns of the first shielding layer and the second shielding layer are the same, and the positions of the first shielding layer and the second shielding layer relative to the base layer are completely the same; The thickness of the first anti-reflection layer and the second anti-reflection layer are both 0.1-10 μm, and the refractive index is both 1-4; The thickness of the base layer is 0.01-5 mm, and the refractive index is 1-3.

2. The transparent electromagnetic shielding film according to claim 1, characterized in that The grid pattern is arranged in a periodic arrangement or a non-periodic arrangement; Preferably, the thickness of the metal layer is 0.05 to 10 μm; Preferably, the material of the metal layer is selected from at least one of a conductive metal and a conductive alloy.

3. The transparent electromagnetic shielding film according to claim 1, characterized in that Preferably, the material of the first anti-reflection layer and the second anti-reflection layer is selected from at least one of Nb2O5, TiO2, ZnO, ZrO2, MgF2, SiO2, Ge, ZnS, ZnSe, AlF3, Al2O3, HfO2, Ta2O5, YbF3, YF3, and SrF2; Preferably, the first anti-reflection layer and the second anti-reflection layer are made of the same or different materials.

4. The transparent electromagnetic shielding film according to claim 1, characterized in that Preferably, the material of the base layer is selected from transparent materials with a transmittance of ≥ 90%.

5. The method for preparing the transparent electromagnetic shielding film according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: providing a base layer, depositing a first anti-reflection layer on the lower surface of the base layer, and depositing a second anti-reflection layer on the upper surface of the base layer; S2: depositing a first metal layer and a second metal layer on a side of the first anti-reflection layer away from the base layer and a side of the second anti-reflection layer away from the base layer respectively; coating a first photoresist and a second photoresist on a side of the first metal layer away from the first anti-reflection layer and a side of the second metal layer away from the second anti-reflection layer respectively, marking at least two positioning points in one of the first photoresist and the second photoresist, and exposing one of the first photoresist and the second photoresist to form a first grid pattern; Then, another photoresist is used to capture the positioning points and position the exposure to form a second grid pattern that is completely aligned with the first grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

6. The preparation method according to claim 5, characterized in that: Step S1 deposits the first anti-reflection layer and the second anti-reflection layer by magnetron sputtering. The conditions of the magnetron sputtering include: a vacuum degree of 1.0×10 -4 ~3.0×10 - 3 Pa, the deposition atmosphere is an inert gas or a mixed atmosphere of an inert gas and O2, the gas flow rate is 20-80sccm, and the sputtering power is 50-200W; Preferably, after the first anti-reflection layer and the second anti-reflection layer are prepared, step S1 further includes an annealing process, and the specific steps are as follows: the side of the first anti-reflection layer away from the base layer and the side of the second anti-reflection layer away from the base layer are subjected to ultraviolet light irradiation treatment, wherein the wavelength of the ultraviolet light is 240 to 300 nm, and the power is 100 to 150 mW / cm 2 The irradiation time is 10 to 20 minutes.

7. The preparation method according to claim 5, characterized in that: Step S2: depositing the first metal layer and the second metal layer by magnetron sputtering, wherein the conditions of the magnetron sputtering include: a vacuum degree of 1.0×10 -4 ~3.0×10 -3 Pa, the deposition atmosphere is an inert gas, the gas flow rate is 20-80sccm, and the sputtering power is 30-200W.

8. The preparation method according to claim 5, characterized in that: Step S2: The specific steps of forming the first grid pattern and the second grid pattern include: using a mask photolithography method: covering the surface of the first photoresist and the second photoresist with a mask having a grid pattern, marking at least two positioning points in one of the first photoresist and the second photoresist, and exposing one of the first photoresist and the second photoresist to form the first grid pattern; capturing the positioning points according to visible light or infrared light to fully align the mask covering the surface of the first photoresist and the second photoresist; exposing the other photoresist covered with the mask to form the second grid pattern; Alternatively, a maskless direct-write exposure method is used: at least two positioning points are marked in one of the first photoresist and the second photoresist, and one of the first photoresist and the second photoresist is exposed to form the first gridded pattern, and the coordinates of the positioning points are recorded as first coordinates; the positioning points are captured on the other photoresist and recorded as second coordinates; the position of the second exposure is obtained by calculating the first coordinates and the second coordinates, and the other photoresist is exposed to form the second gridded pattern that is completely aligned with the first gridded pattern.

9. The preparation method according to claim 5, characterized in that: After forming the first grid pattern and the second grid pattern, step S2 further includes a development step: developing the first photoresist and the second photoresist after exposure, retaining the photoresist in the first grid pattern and the second grid pattern, and removing the remaining photoresist.

10. The preparation method according to claim 9, characterized in that: After the development is performed, step S2 further includes the following steps: wet etching the developed film material to retain the first metal layer and the second metal layer corresponding to the first grid pattern and the second grid pattern, and remove the remaining metal layers; Then, the photoresist in the first grid pattern and the second grid pattern is removed to obtain a metal layer having the first grid pattern and the second grid pattern. At this time, the preparation of the first shielding layer and the second shielding layer is completed.

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